Week 2 - Proteins Flashcards
(24 cards)
Protein/Polypeptide
A chain of amino acids linked by peptide bonds; “polypeptide” is the raw chain, “protein” is the folded, functional version.
Residue
A single amino acid unit in a polypeptide chain.
Carboxyl Group (–COOH)
The acidic end of an amino acid; participates in peptide bond formation.
Amino Group (–NH₂)
The basic end of an amino acid; also involved in peptide bonding.
Alpha Carbon (Cα)
The central carbon in an amino acid, bonded to the amino group, carboxyl group, hydrogen, and R group.
Variable Region/R Group
The side chain on an amino acid that determines its unique chemical properties.
Functional Group
A specific group of atoms within molecules that determine chemical behavior (e.g., hydroxyl, amino, carboxyl).
Peptide Bond
A covalent bond between the carboxyl group of one amino acid and the amino group of another.
Primary Structure
The linear sequence of amino acids.
Secondary Structure
Local folding due to hydrogen bonding:
Alpha Helix
Spiral-shaped; H-bonds within one strand.
Beta Sheet
Flat, pleated sheet; H-bonds between strands.
Tertiary Structure
The 3D shape of a single polypeptide due to R-group interactions (hydrophobic, ionic, disulfide bridges, etc.).
Quaternary Structure
The assembly of multiple polypeptides into one functional protein (e.g., hemoglobin).
Folding
The process by which a protein assumes its functional 3D structure.
N-Terminus
The end of a polypeptide with a free amino group (usually written first).
C-Terminus
The end of a polypeptide with a free carboxyl group.
Denaturation
Loss of a protein’s shape and function due to heat, pH, or chemicals.
Protein Family
Group of proteins with similar structure/function due to evolutionary relationship.
Chaperone
A helper protein that assists other proteins in folding correctly.
Folding Domain
A region of a protein that folds independently and has a specific function.
X-Ray Crystallography
Technique used to determine the 3D structure of proteins at atomic resolution by analyzing how X-rays diffract through protein crystals.
ΔH (Enthalpy change)
Change in heat content; negative ΔH = heat released (favorable).
ΔS (Entropy change)
Change in disorder; positive ΔS = more disorder (also favorable).
